1. Field
The present disclosure relates to a method and an apparatus for preparing a polymeric compound that selectively intercalate and deintercalate oxygen, oxygen-permeable membranes including the polymeric compound, and an electrochemical device using the oxygen-permeable membrane.
2. Description of the Related Art
Recently, electrochemical devices, such as rechargeable secondary batteries using oxygen as a positive active material, for example, lithium air batteries, have drawn attention. In such electrochemical devices, oxygen is externally supplied (from the air or an external oxygen supply unit) in a discharging operation, which is then involved in oxidation reduction reactions in electrodes during charging and discharging operations. Thus, in electrochemical devices, such as lithium air batteries using oxygen in a redox reaction, for example, a lithium air battery, rapid and efficient introduction of oxygen into the device is becoming an important issue in view of electrical capacity maximization. In particular, because oxygen in the air is supplied into an electrochemical device, an efficient way to introduce oxygen from the air, including other components, such as nitrogen, is desired. To this end, a member capable of selectively binding (intercalation/deintercalation) to oxygen molecules may be disposed at an oxygen inlet near a positive electrode (air electrode) of an electrochemical device.
As a material capable of selectively binding oxygen, a cobalt porphyrin derivative of a core of a porphyrin molecule coordinated to cobalt is known. The cobalt porphyrin derivative has the same shape as hemoglobin and may selectively or reversibly bind an oxygen molecule through the permeation of oxygen. In a polymer membrane, in which the cobalt porphyrin derivative is included as an oxygen carrier, oxygen is selectively introduced into the polymer membrane and the oxygen moves rapidly therein. Accordingly, the polymer membrane including the cobalt porphyrin derivative may selectively enable permeation of oxygen, and as a consequence, more research is being conducted now than before focused on the industrial applicability of the polymer membrane as an oxygen selective permeable membrane or an oxygen enrichment membrane.
However, because the cobalt porphyrin derivative is a rigid molecule that lacks flexibility, a polymer backbone other than the porphyrin derivative or a polymer material separately mixed has to be used in large amount in a conventional membrane to achieve high workability and free-standing membrane property. Accordingly, a sufficient selective intercalation and deintercalation function of the cobalt porphyrin derivative and an oxygen permeability function of the membrane using the cobalt porphyrin derivative are difficult to achieve. Also, the membrane having the cobalt porphyrin derivative as a main material has a pressure difference before and after the formation of the membrane that is equal to or greater than oxygen partial pressure in the air and thus, the selective permeability of oxygen is low.
Accordingly, a demand for a polymeric compound having improved selective permeability of oxygen, an oxygen permeable membrane using the polymeric compound, and an electrochemical device using the oxygen permeable membrane still exist.